Whats her citizenship? If she is US citizen or green card holder she doesn't require a visitor visa, other wise she has to apply to one of the Canadian offices in the US. http://www.cic.gc.ca/english/visit/index.html
If she is a citizen of India or not a green card holder in US, she will have to apply for temporary residence visa (TRV) thro one of the canadian consulates in US. If she applies by post, it usually takes about 3-4 weeks. But if she or a representative goes to the consulate and applies in person, she may be granted visa on the same day. For a list of canadian visa offices closest to you, refer: